INVESTIGADORES
JOBBAGY GAMPEL Esteban Gabriel
artículos
Título:
Remote sensing estimates of supplementary water consumption by arid ecosystems of central Argentina
Autor/es:
CONTRERAS, S; JOBBAGY, EG; VILLAGRA, PE; NOSETTO MD
Revista:
JOURNAL OF HYDROLOGY
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Año: 2011 vol. 397 p. 10 - 22
ISSN:
0022-1694
Resumen:
Besides precipitation inputs, evapotranspiration of irrigated and natural oases, i.e. riparian and phreatophytic
ecosystems, of rain-shadow deserts is strongly influenced by lateral water inputs supplied by
mountain rivers and foothill-recharged aquifers. A better understanding of these supplies and their
imprint on the water consumption of those inflow dependent ecosystems (IDEs) across arid regions is
critical to manage agricultural outputs and ecosystem conservation, and the hydrological trade-offs that
emerge among them. Actual operative satellite and physically-based algorithms able to map evapotranspiration
(ET) rates at regional scales still fail when they are applied in ungauged regions because of their
high parameterization and meteorological data requirements. We introduce an ecological and satellitebased
approach to explore the impacts of external water supplies on arid ecosystems, focusing on the
Central Monte desert and its water supplies from the Andean Cordillera, in Argentina. Mean annual precipitation
(MAP) and the Enhanced Vegetation Index (EVI) from MODIS imagery, used as a surrogate of ET,
were the input variables of our empirical model. Two related biophysical indexes were generated for the
whole territory of interest based on a MAPEVI regional function calibrated for the region: the EVI Anomaly
(i.e. deviation from a reference with similar MAP) and the ET Anomaly (i.e. additional water consumption
besides MAP). These indexes allowed us to identify IDEs and to quantify the impact of remote lateral
inflows as well as local constrains on the water balance of rangelands, and irrigated and natural oases.
The performance of this satellite-based approach was evaluated through comparisons with independent
ET estimates based on plot (known crop coefficients) and basin (measured water budgets) scale
approaches. Relative errors in the 218% range at plot and basin scale are in agreement with those uncertainties
reported by other satellite and physically-based approaches. Our approach provides a simple yet
robust diagnostic tool to characterize water balance in arid regions, aimed to improve the identification
of inflow dependent ecosystems and their management under the demanding pressures of land use and
climate change.